Discharge tube



Patented Dec. 1,1931

UNITED STATES r'A'laia'r;caricafffr2 Burman. van nu roi., 011I muevan, m assrenoxnr aa- -srennmrrsuro nemo conrona'rxoir or marca. or Naw Yoan, 1r. y., A conre- RATION I niscnnfen ma application mea october is, im. sensi no. suoi, una "in the mm1-ima :sn-nary as, im. Y

rovide such a construction of tubes of this' 'nd that their manufacture can be easily and exactly effected.

The invention also includes the process ac- `cording to which these tubes can be manufactured.

The discharge tube according to theinvention is distinguished from other tubes in that the grid or ids consist of a number oflrings or groups o one or more wire rings or turns lyin close to or against each other w h11e the ano e when lying in the same cylindrical surface also consists of wire rings or turns which are mutually connected and are located ybetween the groups of the grid.

A articularly simple construction is obt meg vwhen the group of conductors pertaining to the anode, as well as the group or groups pertaining to the grid or ds,are each assembled into one or more helical windrglShe process accordingto the invention is characterized in that the rings or turns pertaining to the anode or to the grid or both kinds of rings or turns are laid around a mandrel which is removed a ain after the anode and grid portions have n fixed mutually as well as relatively to each other by means of carriers which at the same time may serve as leading-in members, and by means of connecting wires, if any.-

According to the invention, if the anode and the grid consist of helical windings, use can be made of a mandrel on the outer surface of which a multiple screw thread is provided and which after the anode and the grid have been wound and fixed, is screwed back out-of these iilembers. d u F 1 In t e accompanying rawings, igure represents an embodiment of an electrode construction according to the invention, and Figure 2 represents a mandrel which can be used for the manufacture of this construction.

The grid according to Figure 1 has been helicall wound out of three wires 1, 2 and 3, lying c ose to and against each other. Au

anode wiref4 has been helically wound in the same cylindrical surface between the grid windings and slightly spaced supports thencfrom. At their ends thefgrid wires 1, 2 and 3 are fixed in supports 5 and 6 which are sealed in the pinch (not shown) of the stem of the lamp and either of which may be used to con duct the o'rid current. The anode wire 4 is supported by su ports 7 and 8 to which the same remark app es as that made for the supports 5 and 6.

An incandescent cathode 9 runs axially through the tubular body formed by the wires 1--4 and is supported by the lead wires 10 and 11.

The whole is enclosed or sealed in any known manner in an envelope, such as a bulb 18 consisting wholly or partly of glass, which bulb thereupon is exhausted.

In order to obtain a uniform field it is advisable to choose the pitch of thescrew thread so as to be not larger than the radius of the cylinder on which the helix is wound. When using annular anodeand grid portions, the distance between two successive rings of like nature, measured from centre to centre, takes the cplace of the pitch of a helical grid or ano e.

In the manufacture of the electrodes it is advantageous to make use of the mandrel re resented in Figure 2. It consists of a cy indrical body 12 of refractory material such as tungsten in order to be able to anneal the anode and the grid on themandrel. A narrow screw thread 13 and a second wider screw thread 14 which is as deep as 13, are provided in the outer surface of the body 12. Between the two screw threads there remain ridges 15 and 16 which determine the distance between the anode and the grid. At one end the mandrel terminates in a smaller, square portion 17 by which it can be turned. The grid wires 1--3 and the anode wire 4 may e wound simultaneously or successively on the mandrel; they are fixed in the stem of the tube by means of their respective supports 5-6 and 7-8` and then, if desired, annealed, whereupon the mandrel can be screwed back out of the cylinder. Thereupon a cathode wire 9 can be provided.

It will be obvious that the anode or the grid or both of them, instead of being made rom round wires can also be wound from fiat wires, 'in which case the grid ma also con- 6 sist of a singlewide fiat band an the anode of a narrower one. This will tend to simplify the manufacture; The' amplification factor o f a triode -being a function of the ratio of the capacities gridl filament and anode-filament, any desired value '(provided it is not too large) of the said factor can be obtained by a suitable choice of the ratio between the surface of the v grid: and that of the anode. In the example l 1 lustrated the amplification factor will be about equal to 3.

What I claim is: 1. An electron dischar tube, comprising a straight cathode, an an e consistin of a coil of wire wound in the form of a he x and a id consisting of a coil of wire wound in the orm of a helix the two helices being so interwoven that each windin of the anode is adjacent on each side to a p urality of windings of the grid. 4

2. An electron dischar e device comprising a heatable straight catho e for emitting electrons, and two cooperating electrodes in the form of two helices of the same diameter and pitch coaxially disposed to lie in the same cylindrical surface about said cathode with each turn of one helix lying between two adjacent turns of the other helixand the turns of one of said helices being so spaced that a substantially uniorm electrostatic field exists between the adjacent turns of said helix when said helix is at normal operating potential. 3. An electron discharge device comprising a heatable electron emitting cathode, all anode and a grid in the form of two helices of the same diameter and pitch and both coaxial with said cathode, the turns of said grid having a greater width than the turns of said anode, and each turn of said anode lying between adjacent turns of said grid.

- In testimon whereof I aiiix my signature j at the city o Eindhoven, this 16th day of September, A. D. 1925.

- BALTHASAR vAN DER POL. 

